Scavengers of reactive oxygen intermediates do not mediate the depression of macrophage hydrogen peroxide production caused by erythrocyte phagocytosis

Respiratory burst capacity of activated macrophages is resistant to depression by erythrocyte phagocytosis

The present study evaluated whether macrophage activation would reduce the depression in the capacity of macrophages to produce H2O2 following EIgG phagocytosis. Macrophage activation was accomplished by exposing inflammatory rat peritoneal macrophages to 10 units of IFN gamma for 72 h. IFN gamma treatment caused a four to fivefold increase in phorbol myristate acetate (PMA)-triggered H2O2 production, but Fc receptor phagocytic function was unaltered. IFN gamma-activated macrophages were able to phagocytize a greater number of EIgG before a decrease in PMA-triggered H2O2 production was observed and the level of H2O2 production did not fall below that of untreated-inflammatory macrophages that had not received an EIgG phagocytic challenge. The depression in Fc receptor phagocytic function was unaltered with macrophage activation. These results indicate that activated macrophages are resistant to the depression of respiratory burst capacity caused by erythrocyte phagocytosis and suggests that IFN gamma treatment may be effective in preventing the impairment of host defense against bacterial infection that is associated with erythrocyte phagocytosis.

Macrophage hydrogen peroxide production and phagocytic function are decreased following phagocytosis mediated by Fc receptors but not complement receptors

Previous in vivo and in vitro studies have shown that the phagocytosis of IgG-coated erythrocytes results in a depression of macrophage function. The present study compared the effect of phagocytosis mediated by Fc receptors with that mediated by complement receptors. The phagocytosis of IgG-coated erythrocytes by elicited peritoneal macrophages depressed their capacity to produce hydrogen peroxide as well as phagocytic function. Phagocytosis of erythrocytes coated with IgM and complement had neither of these effects. These results implicate the intracellular signaling that results from Fc receptor mediated phagocytosis in the depression of macrophage function that is caused by phagocytosis.